The point I'm making is that some people in our profession think they are slacking when they're not, for the reasons I described. OP's description doesn't convince me that they necessarily are. In particular the comment at the end about having spent the years prior to the pandemic "pretending" to themselves that they were working hard sounds to me like somebody who's never really understood their own mental processes and has encountered a different perspective by doing the job in a different environment. I might be wrong, but that sounds more likely to me than that they have been getting away with minimal contributions throughout what they describe as a 20 year career. Your report didn't get away with it - the evidence is always there in the commit history, and the 2-5 year job length OP mentions is, contrary to their assessment, plenty of time to judge a developer's productivity.
Another hint is the fact that this person is seriously proposing the idea that everybody else is slacking off and lying too. This indicates that they don't think their actual output is less than other developers'.
As I say, I may be wrong. I don't know this developer - these are just some thoughts based on what they've posted. Unlike some here I'm not assuming I know the truth.